bug#41200: Displaying a tooltip with x-show-tip gets very slow as more faces are defined

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Cc: Eli Zaretskii <eliz@gnu.org>,  41200@debbugs.gnu.org
> Date: Wed, 20 May 2020 00:48:55 +0300
> 
> >>> +  :group 'basic-faces)
> >>> +
> >>> +  :group 'basic-faces)
> >>>
> >>> -  :group 'tab-bar-faces)
> >>> -
> >>> -  :group 'tab-line-faces)
> >> 
> >> Could these faces belong to both groups?
> >> 
> >>   :group 'basic-faces
> >>   :group 'tab-bar-faces
> >
> > Yup, but that won't work well if the face is customized before the
> > group is defined, right?  Maybe the trick would be to add the group to
> > the face when tab-bar.el and tab-line.el are loaded?
> 
> Actually since tab-bar.el is pre-loaded this problem exists only for
> tab-line.el.
> 
> Then adding something like
> 
>   (nconc (get 'tab-line-faces 'custom-group) '((tab-line custom-face) ...))
> 
> to tab-line.el will add faces when tab-line.el are loaded.

Could you guys please finalize these issues?  I'd like to install
these changes on master, for which I'd need a patch that covers both
the changes in the face storage and the fix for the tab-line face.

Actually, the problem with the tab-line face will probably need to be
fixed on emacs-27.

Thanks.